(NaturalNews) Popeye was right; eating spinach really does help build muscle strength and improve cellular function, according to a new study released by the Swedish medical school Karolinska Institutet. A follow-up to a similar study released by the school back in the 1990s, researchers again observed that the natural nitrates found in spinach and other leafy greens feed muscular mitochondria, and thus help regulate blood pressure, immune defense, and cell metabolism.

Inorganic nitrates, which are different than the synthetic nitrates commonly added to processed foods, are used by the body to produce nitric oxide (NO), a vital molecular component that delivers oxygen to blood and performs a variety of other physiological and pathological processes in the body. NO is a powerful anti-inflammatory, anti-thrombotic, and vasodilation agent, all of which result in numerous health benefits.

And it turns out that spinach is loaded with these nitrates, which are converted into NO and used throughout the body. Professors Eddie Weitzberg and Jon Lundberg, coauthors of the Swedish study, observed that consuming the nitrate equivalent of 200-300g of spinach for just three days along with intense exercise improves mitochondrial efficiency. This in turn reduces oxygen consumption and increases the production of energy-rich substances in muscle tissue, resulting in both improved muscle gains and better overall health.

"The mitochondria play a key role in cellular metabolism," said the authors. "Improved mitochondrial function probably has many positive effects on the body, and could explain some of the health benefits of vegetables."

Besides improving muscle growth and cellular health, the NO-producing substances in spinach also help treat diseases like diabetes and heart disease, which are a product of mitochondrial dysfunction. Since NO helps reduce blood pressure, it is capable of warding off diabetes in pre-diabetic individuals, as well as reducing strain on the heart, which can lead to heart attack or stroke.